There's a certain type of westernised Iranian. Not the plastinated Tehrangelinos held up for ridicule in the TV series Shahs of Sunset. Highly educated, wealthy, into contemporary art and fashion, they are more likely to call New York home, but can be spotted in London, Paris or Basel too. You might catch them at a gallery opening, a GQ party, or sitting in a cafe leafing through the latest issue of Monocle or Bidoun.

This is the subspecies to which Hooman Majd (pictured) appears to belong. An ambassador's son, his career embraces writing for the New Yorker and designing menswear for his fashion label, House of Majd. Now in his 50s, he's smokily good-looking and always impeccably turned out; suave, well-connected and perhaps a little smug. There are worse crimes, of course. But his public image seeps into his political and observational writing on Iran – this is his third book about the country – and if you're not charmed by that sort of thing, you'll find it distracting.

I did, but I also found myself engrossed. Many of his stories will have a familiar ring to semi-detached Iranians like me, either from paranoid fantasy or actual experience. Such as his description of a hair-raising weekend in Tehran, when, having been pulled aside at immigration, he was given instructions to attend the Ministry of Culture and Islamic Guidance a day or two later. What awaited him was a classic entanglement with the Iranian state: an experience that would've been funny if it hadn't been so laden with menace. He had to wait, sweating, and then spend three hours with a couple of goons who seemed to have read everything he'd ever written. This is a bureaucracy that isn't efficient or single-minded enough to eliminate all dissent. As Majd points out, the Islamic republic is less of a police state than the regime run by the shah. But it lashes out unpredictably, stopping some at airports and letting others go, imprisoning the unlucky ones and subjecting the others to mildly comic, if disconcerting, interviews.

The incident came just after he'd decided to move with his young wife, Karri, and their infant son, Khashayar (Khash for short), to Iran for a year. Despite his encounter, they pressed ahead with their plans, which were motivated in part by Majd's desire to reconnect with a home he'd never really known (his youth was spent shuttling between boarding school and various foreign capitals), and to give Khash a kind of baptism in Iranian culture.

Majd's analyses of that culture are occasionally superficial. The usual badges of pride and shame that Iranians are fond of displaying to outsiders are trotted out. Among the qualities he cites are a propensity to sulk ("boy do Iranians know how to sulk"), to stare, to party ("boy do we like our parties"), to be fatalistic and to be nosy. His politics are interesting, though, as he is something of a reformist insider. His links to various bigwigs, and his family connection to the former president, Mohammad Khatami, are mentioned more than they need to be. But they shed light on the internal dynamics of what is too often presented as a monolithic political culture. The Ministry of Guidance actually has little to fear from Majd, who is no enemy of the Islamic republic. He understands how it got there, and doesn't presume to know what's good for Iranians better than Iranians themselves – most of whom want evolution, not revolution.

But he is more impressive on the human than the political. There are some nice pen portraits of the partygoers, taxi-drivers and bored babysitters who help make Tehran's streets come to life. The Iranian attitude to children – far more indulgent and demonstrative than in Europe or America – is beautifully captured. Khash is mollycoddled by an assortment of baristas, doormen and other strangers, with one young man in a park even spontaneously scribbling down a poem for him. There is a powerful section in which Majd wanders with a friend around the neighbourhood where his grandparents lived, and which he only dimly recalls, partly through the smell of the mud walls, the trees and the gutter.

And this is the nub of the book: it is subtitled "An American Family in Iran", but Karri is two-dimensional and Khash just a baby. Majd's relationship with his Iranian past is the real subject. He writes from the point of view of someone whose "home" is an unfamiliar place. Whose clerical ancestors are about as far from New York socialites as you could possibly get. The book ends with a postscript on his father, who had been living in London, and died shortly after the family ended their year abroad. It's a resolution of sorts to a dislocated life: "It was a little ironic," he writes, "but fitting and gratifying ... that the man who had been my bridge to another world, the half that was a part of me but that I didn't know growing up, was now looking to me to be his bridge."